The background description provided here is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Residual surface and embedded charge may be created on a substrate such as a semiconductor wafer during processing. For example, residual surface and embedded charge may be created during dry etching. Substrate processing systems for performing dry etching typically include a processing chamber, a gas distribution device such as a showerhead and a substrate support. A substrate such as a semiconductor wafer may be arranged on the substrate support. In some examples, the substrate support includes an electrostatic chuck (ESC). During processing, different gas mixtures may be introduced into the processing chamber. During the process, the substrate support may be biased by DC or radio frequency (RF) power.
During processing, substrates are often subjected to wet spin-clean processes to remove chemicals and/or particles either before or after a process. During wet cleaning, the substrates may be subjected to a liquid such as a rinsing liquid that is dispensed onto the substrate as it is rotated. Loss of yield can be directly linked with wet-clean processes that are conducted on substrates having residual surface and embedded charge. Arcing-related defects (or volcano defects) are the most likely mechanism behind the yield decrease.
To prevent damage to the substrate and/or defects during subsequent processing, efforts have been made to reduce or eliminate the residual surface and embedded charge. Techniques for reducing residual surface charge include corona discharge, soft X-ray photo-ionization, and alpha particle-ionization. For example, ion-assisted wafer discharge generates positively-charged and negatively-charged ions close to a surface of the substrate. Free charge carriers (ions) are attracted to a surface of the substrate due to the presence of a charge on the substrate. The free charge carriers counteract charge at the surface of the substrate. However, the ions cannot penetrate into the substrate to reduce the embedded charge.